Question

Please help me with this question, I have no idea how to set it
upor solve it. Thanks!

A hollow, thin-walled insulating cylinder of radius R and length
Lhas charge Q uniformly distributed over its surface. (a)
Calculatethe electric potential at all points along the axis of the
tube.Take the origin to be at the center of the tube, and take
thepotential to be zero at infinity. (b) Show that if L <<
R,the result of part (a) reduces the potential on the axis of a
ringof charge of radius R. (c) Use the result in part (a) to find
theelectric field at all points along the axis of the tube.